Disturbances in movement coordination are the least well understood but often the most debilitating with respect to functional recovery following stroke. These deficits in coordination are expressed in the form of abnormal muscle synergies and result in limited and stereotypic movement patterns that are functionally disabling. The result of these constraints in muscle synergies is an abnormal coupling between shoulder abduction and elbow flexion, which significantly reduces a stroke survivor's reaching space when he/she lifts the weight of the impaired arm against gravity. Current neurotherapeutic approaches to mitigate these abnormal synergies have produced, at best, limited functional recovery. In an effort to remediate this shortcoming the current project proposes to fully develop and examine the effectiveness of a novel 3-D force controlled robot arm that allows persons with stroke to progressively overcome the negative effects of the weight of their limb during functional movements. The specific objective of this development project is to adapt a 3-D force controlled robot arm, the HapticMASTER (HM), to a Biodex System 3 seating system and integrate it with a compact real-time 3-D visual display to generate an upper extremity rehabilitation device that implements a virtual mechanical environment. There is a current deficiency in rehabilitation science calling for a device that has the capacity to both accurately evaluate and deliver highly controlled patient-specific upper extremity rehabilitation. Development of the Arm Coordination Training 3-D device (ACT3D) for the measurement and rehabilitation of stroke-induced movement discoordination realizes this need. The device will provide high-resolution measurements of physiological (strength and coordination) and functional performance (reaching workspace) evaluating the effectiveness of rehabilitation interventions. Therefore, quantitative outcome measures will be obtained and may be used to evaluate patient progress. The device will also be designed to deliver novel interventions that train individuals with a broad spectrum of upper extremity reaching impairment to progressively overcome the negative effects of gravity. Furthermore, the ACT3D will be developed to emulate real live scenarios such as reaching and retrieval of objects of different weight in space. The device will interface with the user in a safe and comfortable fashion quickly setup by a healthcare provider. It is anticipated that the ACT3D will directly benefit a large number of individuals who currently suffer from the disabling effects of stroke.